#include<stdio.h>
int gcd(int a,int b){
    while(b!=0){
        int temp=b;
        b=a%b;
        a=temp;
    }
    return a;
int main(){
    int n,m;
    scanf("%d %d",&n&m);
    if(n<0 || m<0){
        printf("Invalid input");
        return 0;
    }
    printf("%d",gcd(n,m));
    return 0;
}